InAsSb bulk materials do not translate well to high performance Long Wave Infra Red photodetectors due to the lattice mismatch. Some work has been done on using nBn designs with Type II Superlattice (T2SL) absorber layers to avoid the lattice mismatch problem. However, due to the poor diffusion of holes in T2SLs, absorber layers need to be doped p-type so that the higher mobility electrons are the minority carriers. T2SLs doped n-type will inevitably have limited quantum efficiency. [e.g., see Lee et al., “Subband transitions in dual-band n-B-n InAs/GaSb superlattice infrared photodetector identified by photoresponse spectra” in Appl. Phys. Lett 95, 102106 (2009).]
Dual band photodetectors have been based on pNp or n-p-B-p-n T2SL architectures. Dual-band functionality has been demonstrated for LWIR and VLWIR detectors using this architecture. For example, NWU has published data using this type of design [Appl. Phys. Lett 92, 111112 (2008)].